Special Sensor J (SSJ) was an electron spectrograph with one fixed cahnnel and one stepping channel. The channels detected energetic electrons over ranges of energies associated with visible aurora. The fixed channel was 6 keV and the stepping channel cycled through eight energy thresholds: 54, 98, 219, 600, 1400, 3540, 8200, and 1970 eV. The data sample was taken approximately every second. The field-of-view was 3 degrees by 12 degrees.